Complement activates neutrophils during PTCA procedure in patients with unstable angina pectoris

Relationship between Lp-PLA2 and in-stent restenosis after coronary stenting: a 3-year follow-up study

BACKGROUND AND AIMS

Coronary in-stent restenosis (ISR) is an important complication of percutaneous coronary intervention (PCI). However, the relationship between lipoprotein associated phospholipase A2 (Lp-PLA2) level and ISR after PCI is rarely reported. This study aims to explore the relationship between Lp-PLA2 and the occurrence of ISR at post-PCI and its predictive value for ISR.

METHODS AND RESULTS

Plasma Lp-PLA2 mass were measured in 847 patients planting 1262 stents and evaluated along with known risk indicators. One-year angiographic follow-up showed that baseline elevated Lp-PLA2 mass was strongly associated with early restenosis (95% CI = 1.062-3.050, P < 0.05). Beyond the first year, the occurrence of late restenosis (95% CI = 1.043-3.214, P < 0.05) was significantly larger in the elevated Lp-PLA2 group. Kaplan-Meier analysis after three-year clinical follow up suggested that Lp-PLA2 mass did add the positive effect on the occurrence of major adverse cardiovascular events (MACEs).

CONCLUSION

In conclusion, increased baseline plasma Lp-PLA2 predicts increased risks of re-stenosis and MACEs, which may be a novel biomarker for predicting ISR and MACEs.

Immunological aspects of chronic venous disease pathogenesis

Chronic venous disease (CVD) is a very common health problem concerning up to 1/3 of the society. Although venous hypertension and valvular incompetence have been long known to be crucial for development of the illness, its exact aetiology remains unclear. Recent findings indicate that inflammatory processes may be crucial for development of incompetent valves and vein wall remodelling. One of the most interesting theories describes “leucocyte trapping” as the mechanism responsible for elevated vein wall permeability and oxidative stress in the veins. At the same time, the cytokine profile of the blood in incompetent veins has not been thoroughly examined. Popular anti-inflammatory drugs relieve some symptoms but do not have much proved effects in prevention and treatment.

We intend to summarize the existing knowledge of the immunological aspects of CVD in order to emphasize its importance for understanding the aetiology of this illness. We also wish to indicate some aspects that remain to be studied in more detail.

Complement factor concentrations in patients with acute myocardial infarction: time course and ability to predict left ventricular dysfunction

Aim: Inflammatory processes may contribute to myocardial ischemia/reperfusion injury after myocardial infarction (MI). We aimed to evaluate the predictive value of complement factor concentrations for the occurrence of post-MI left ventricular (LV) dysfunction. Patients & methods: Fifty-five patients with acute MI were included. Complement factors and CRP were assessed at hospital admission (HA) and during the first 3 days. LV ejection fraction was determined by echocardiography before hospital discharge. Results: Total hemolytic complement (CH50) on admission and peak CRP during the first hospitalization days were higher in patients who developed LV dysfunction (LV ejection fraction ≤45%). By contrast, neither absolute concentrations of single complement factor concentrations nor changes in these concentrations over time were associated with the occurrence of LV dysfunction. CH50 at HA was independently associated with LV dysfunction. Conclusion: This study generates the hypothesis that CH50 concentration at HA in patients with acute MI may identify individuals at high risk for LV dysfunction.

Complement Component C5a Predicts Restenosis After Superficial Femoral Artery Balloon Angioplasty

PURPOSE

To investigate whether balloon angioplasty of the superficial femoral artery (SFA) increases serum levels of C5a and whether C5a predicts risk of restenosis.

METHODS

C5a antigen was measured at baseline and 8 hours after intervention in 131 consecutive patients (76 women; median age 72 years) with intermittent claudication who underwent successful primary SFA balloon angioplasty. Patients were followed for a median 10 months [interquartile range (IQR) 6 to 14] for the occurrence of >50% restenosis by duplex ultrasound.

RESULTS

Median C5a levels increased significantly from 39.7 ng/mL (IQR 27.8 to 55.0) at baseline to 53.8 ng/mL (IQR 35.6 to 85.1, p<0.001) 8 hours post intervention. During the follow-up period, 70 (53%) patients developed restenosis. Increasing levels of C5a (quartiles) at baseline were significantly associated with an increased risk for restenosis (p=0.0092). Adjusted hazard ratios (95% confidence intervals) for restenosis with increasing quartiles of baseline serum C5a levels were 1.24 (0.60 to 2.58), 1.93 (0.95 to 3.93), and 2.08 (1.02 to 4.21), respectively, compared to the lowest quartile. This effect was independent of nonspecific inflammation as reflected by plasma levels of C-reactive protein.

CONCLUSION

Inflammatory mechanisms play a major role in the development of restenosis after angioplasty. The complement component C5a exerts strong chemotactic and proinflammatory effects. Enhanced complement activation prior to PTA, as measured by higher levels of C5a, was significantly associated with restenosis after SFA balloon angioplasty. Pathways of complement inhibition thus may be worth investigating with respect to improving patency rates.

Neutrophil Superoxide Anion Generation During Atorvastatin and Fluvastatin Therapy Used in Coronary Heart Disease Primary Prevention

Neutrophil superoxide anion generation was measured during atorvastatin and fluvastatin therapy in patients with coronary heart disease (CHD) risk. The patients were randomly allotted into three groups. The atorvastatin group comprised 17 patients who were administered the drug orally 10 mg a day at bed time. The fluvastatin group consisted of 18 patients on an oral dose of 40 mg once daily at bed time. The control group comprised 12 healthy subjects with no drug administration. Blood samples were collected from cubital vein before and after 6-week therapy with these drugs and once in the control group. Neutrophil superoxide anion generation in whole blood without and with opsonized zymosan (OZ) stimulation was determined using superoxide dismutase from bovine erythrocytes. In the atorvastatin group, statistically significant (P < 0.05) decrease in superoxide anion generation by nonstimulated and OZ-stimulated neutrophils was observed after 6 weeks of therapy. In fluvastatin group, no changes in neutrophil superoxide anion generation were observed after the 6-week treatment period. Our study has shown an additional nonlipid mechanism of atorvastatin used in CHD primary prevention.

Influence of ionic and non-ionic radiographic contrast media on leukocyte adhesion molecules

BACKGROUND: Many papers have focused on the importance of granulocytes in the process of reperfusion and ischemia. Most of the clinical studies measured several parameters of this process during and after coronary angiography, without taking into account the effect of the radiographic contrast media (RCM) used during this procedure. MATERIALS AND METHODS: We performed a randomized patient study (n = 37) to evaluate the effect of ionic and non-ionic RCM on granulocyte adhesion during coronary angiography. We also evaluated the influence of the ionicity and osmolarity of the different substances on granulocyte adhesion molecules in in vitro experiments. RESULTS: The osmolarity of patient serum samples increased from 302 +/- 1 to 309 +/- 1 mOsm/kg (p < 0.05) after infusion of RCM. The CD11b expression in the samples of the non-ionic RCM treated group increased from 221 +/- 21 MFI to 377 +/- 30 MFI (p < 0.05) measured as the absolute mean fluorescence intensity (MFI), yet did not alter significantly in the ionic RCM group. In contrast, the in vitro experiments showed a reduction of the CD11b expression from 360 +/- 70 MFI to 149 +/- 30 MFI (p < 0.05) in the ionic RCM group. CONCLUSIONS: The upregulation of adhesion molecules was significantly reduced in vivo with ionic RCM, while ionic substances caused opposite effects in vitro. This effect should be taken into account when performing leukocyte functional analysis of samples taken during angiography.

Oxidative stress and neutrophil activation—the two keystones of ischemia/reperfusion injury

The widespread introduction of fibrinolytics and recently also PTCA in the treatment of myocardial infarction has changed the picture of modern cardiology. But this therapy also raises new problems and challenges. One of them is the occurrence of extensive tissue injury caused by reperfusion. Reinstitution of oxygen to the ischemic tissues initiates various processes leading to generation of reactive oxygen species (ROSs). Acting on the plasma membrane ROS damage its organization and release various proinflammatory agents. Different proteins, including receptors, ionic channels, transporters or components of transduction pathways are substrates of oxidation by ROSs. Their changed structure results in altered functioning and disruption of vital cellular processes. Another key factor of reperfusion injury is activation and infiltration of infarcted area by polymorphonuclear leukocytes (PMNs). Multiple studies identified consecutive stages of PMN activation and substances being involved in it. Main interest lies in cellular adhesion molecules, particularly selectins and beta2 integrins, as their antagonists were repeatedly found to diminish neutrophil activation and infarct size. Nevertheless new publications strike at the foundations of the established order and confront the relation between neutrophil infiltration and infarct size. PMNs are linked by close ties to other cells involved in inflammatory response. Seemingly also in cardiac ischemia-reperfusion injury, the activity of neutrophils is modulated by lymphocytes and macrophages. The article describes mutual interactions between different factors involved in the reperfusion injury that may enable preparing new treatments, hopefully as effective and successful as reperfusion therapy.

Interleukin 6 expression in coronary circulation after coronary angioplasty as a risk factor for restenosis

OBJECTIVE

To investigate changes in cytokine expression in the coronary circulation induced by percutaneous transluminal coronary angioplasty (PTCA).

METHODS

The study involved 32 patients with ischaemic heart disease who underwent elective PTCA for isolated stenotic lesions of the left coronary artery. Ten patients had plain old balloon angioplasty, 10 had percutaneous transluminal rotational atherectomy, and 12 had stent implantation. Blood samples were drawn from the coronary sinus before and immediately after PTCA. Plasma concentrations of interleukin 6 (IL-6), platelet derived growth factor (PDGF), monocyte chemoattractant protein 1 (MCP-1), and macrophage coronary stimulating factor (M-CSF) were measured. The patients were scheduled for follow up angiography six months after PTCA. Late loss index was calculated using quantitative coronary angiography.

RESULTS

IL-6 concentrations in coronary sinus blood increased immediately after PTCA (p < 0.001), but there was no change in PDGF, MCP-1, or M-CSF. There was a positive correlation between changes in IL-6 concentrations immediately after PTCA and late loss index six months after PTCA (r = 0.73, p < 0.001). IL-6 concentrations in coronary sinus blood were higher in patients with late restenosis than in those without restenosis (p < 0.001).

CONCLUSIONS

PTCA induces IL-6 production in the coronary circulation. This may induce subsequent inflammatory responses in injured vessels and play an important role in late restenosis after PTCA.

Reperfusion injury after focal myocardial ischaemia: polymorphonuclear leukocyte activation and its clinical implications

The only way to rescue ischaemic tissue is to re-instate the oxygen supply to the tissue. However reperfusion of the ischaemic area not only oxygenates the tissue but also initiates a cascade of processes, which may in some cases result in temporary dysfunction of the myocardium. In order to devise protective measures, it is essential to understand the mechanisms and the triggers of this reperfusion phenomenon. In this review we will mainly focus on the inflammatory response caused by reperfusion. We will cover the different steps of polymorphonuclear leukocyte activation and will briefly discuss the molecular biology of the receptors involved. The currently used pharmacological medications in acute cardiology will be reviewed and in particular their actions on polymorphonuclear leukocyte activation, adhesion and degranulation. This review is a compilation of the current knowledge in the field and the therapeutic progress in the prevention of reperfusion injury made today.

Therapeutic potential of complement inhibitors in myocardial ischaemia

Under normal conditions, the complement system functions to eradicate microbes and other membrane bound pathogens. In other situations, complement activation comprises a pivotal mechanism for mediating tissue demolition in inflammatory disorders, including ischaemia/reperfusion injury. Complement-mediated tissue damage has long been recognised as a significant contributor to myocardial reperfusion injury. However, clinical use of complement inhibitors to reduce the extent of irreversible tissue injury related to reperfusion, remains in the early stages of development. Activation of the complement system generates anaphylatoxins, opsonins and the lytic moiety known as the membrane attack complex (MAC). In addition, fragments of the complement cascade proteins (e.g., C3a and C5a) secondarily initiate processes deleterious to myocytes by recruiting and stimulating inflammatory cells, such as neutrophils and macrophages, within the area of reperfusion. Damaged tissue itself, is capable of upregulating the genes that encode the formation of complement proteins leading to assembly of the MAC, which in turn further advances tissue injury. All of these factors contribute to the development of myocardial infarction subsequent to ischaemia and reperfusion. This paper provides an overview of how the complement system operates and examines the various inhibitors, both endogenous and exogenous, that regulate the complement cascade. Activation and inhibition of the complement system will be discussed primarily in the context of myocardial ischaemia and reperfusion injury.